Radiopharm Theranostics Doses First Patient in Phase 1 Clinical Study of RAD 402 in Advanced Prostate Cancer

Rhea-AI Summary

Radiopharm Theranostics (ASX:RADX) has dosed the first patient in the Phase 1 trial of RAD 402, a KLK3-targeting monoclonal antibody radiolabelled with Terbium-161 (Tb161) for advanced prostate cancer. The dose-escalation study will assess safety, whole-body distribution, tolerability and preliminary activity, and determine MTD and/or RP2D.

Preclinical mouse xenografts showed strong tumor targeting, minimal bone/marrow uptake and expected hepatic clearance. The company expects to share data from the first two dose levels in 2H 2026.

Positive

• Phase 1 initiation with first patient dosed
• Preclinical strong tumor targeting in mouse xenografts
• Minimal bone/marrow uptake observed preclinically
• Planned data readout from first two dose levels in 2H 2026
• Tb161 dual emission represents an innovative radiotherapy approach

Negative

• Clinical benefit and safety are unproven until Phase 1 readouts
• MTD and RP2D not yet determined during dose escalation
• Program depends on partners for Tb161 supply and radiolabelling

Market Context

This announcement advances RAD 402 from ethics approval into active Phase 1 testing for advanced pro...

Analysis

This announcement advances RAD 402 from ethics approval into active Phase 1 testing for advanced prostate cancer, with initial data from the first two dose levels expected in 2H 2026. It builds on Radiopharm’s recent clinical momentum in RAD101 imaging and RV‑01 therapeutics. Investors may track safety, biodistribution and dose‑finding outcomes, alongside existing SEC-registered resale capacity under the effective Form F‑3, to assess how clinical progress and potential future capital needs intersect.

Key Figures

Data timing: 2H 2026 Phase: Phase 1 Dose levels: First two dose levels +1 more

4 metrics

Data timing 2H 2026 Planned readout from first two RAD 402 dose levels

Phase Phase 1 First-in-human RAD 402 trial in advanced prostate cancer

Dose levels First two dose levels Initial data planned from first two cohorts

Clinical trial ID NCT07259213 Identifier for RAD 402 Phase 1 prostate cancer study

Previous Clinical trial Reports

5 past events · Latest: Mar 24 (Positive)

Same Type Pattern 5 events

Date	Event	Sentiment	24h Move	Catalyst
Mar 24	RAD101 interim data	Positive	-10.8%	Second interim Phase 2b RAD101 data with 90% PET–MRI concordance in 18/20 patients.
Feb 24	First-patient dosing	Positive	+1.8%	First patient dosed in Phase 1/2a 177Lu‑BetaBart (RV‑01) safety and activity study.
Dec 15	RAD101 interim success	Positive	+149.5%	RAD101 Phase 2b interim showed 92% MRI concordance and selective tumor uptake on PET.
Nov 18	RAD402 trial approval	Positive	-4.8%	Ethics approval to initiate first‑in‑human Phase 1 RAD402 trial in advanced prostate cancer.
Nov 17	RAD101 enrollment update	Positive	+2.6%	RAD101 Phase 2b reached 50% enrollment with early imaging showing selective uptake.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Pattern Detected

Clinical trial news has produced mixed reactions: several positive RAD101 and RV‑01 updates saw strong gains, while other seemingly positive trial milestones (including RAD 402 ethics approval and recent RAD101 data) were followed by selloffs, indicating inconsistent trading responses.

Recent Company History

Over the last six months, Radiopharm has steadily advanced multiple radiopharmaceutical programs. RAD101 imaging data in brain metastases twice achieved ≥90% concordance with MRI, with one interim readout driving a 149.53% move. The company also progressed first‑in‑human studies, dosing initial patients in trials such as 177Lu‑BetaBart (RV‑01) and securing ethics approval for RAD 402. Today’s first‑patient dosing for RAD 402 builds directly on the November 2025 approval to initiate this prostate cancer Phase 1 trial, extending the clinical footprint beyond brain metastases imaging.

Key Terms

phase 1, monoclonal antibody, radiotherapies, radiolabelled, +4 more

8 terms

phase 1 medical

"first-in-human Phase 1 clinical trial of RAD 402"

Phase 1 is the first stage of testing a new drug or medical treatment in people, focused primarily on safety, how the body handles the product, and finding a tolerated dose. Think of it as a short, tightly controlled experiment with a small group to check for dangerous side effects before wider testing; for investors it is an early milestone that reduces some uncertainty but still carries high risk and potential for both big value changes and setbacks.

monoclonal antibody medical

"RAD 402, a monoclonal antibody targeting KLK3 radiolabelled with Terbium 161"

A monoclonal antibody is a laboratory-made protein designed to recognize and attach to a specific target in the body, such as a disease-causing substance or cell. It functions like a highly precise lock-and-key tool, helping to treat or detect illnesses. For investors, companies developing monoclonal antibodies can represent promising opportunities in the healthcare sector, especially as these treatments often address unmet medical needs.

radiotherapies medical

"represents an innovative approach for radiotherapies in Prostate Cancer"

Radiotherapies are medical treatments that use controlled beams of radiation to damage or destroy abnormal cells, most commonly cancer, while sparing nearby healthy tissue as much as possible. For investors, they matter because development, approval, and adoption of these treatments drive sales, require specialized equipment and regulatory clearance, and influence reimbursement and long-term clinical outcomes—factors that affect a company’s revenue, risks, and growth prospects.

radiolabelled medical

"a monoclonal antibody targeting KLK3 radiolabelled with Terbium 161"

Radiolabelled describes a drug, diagnostic agent, or molecule that has a tiny amount of radioactive material attached so its path and behavior can be tracked inside the body. For investors, radiolabelling matters because it enables precise measurement of where a product goes, how long it stays, and how well it works or targets disease—like putting a bright, invisible tracker on a parcel to prove delivery—impacting development speed, regulatory clearance, safety handling, and commercial value.

maximum tolerated dose medical

"designed to determine the Maximum Tolerated Dose (MTD) and/or recommended"

Maximum tolerated dose is the highest amount of a substance, such as a medication or chemical, that can be used without causing unacceptable side effects or harm. It’s like finding the maximum speed you can drive without risking a ticket or accident. For investors, understanding this concept helps gauge how much risk or exposure is safe or sustainable in a given situation.

recommended phase 2 dose medical

"Maximum Tolerated Dose (MTD) and/or recommended phase 2 dose (RP2D)"

Recommended phase 2 dose is the specific drug amount chosen after initial human studies to use in mid-stage clinical trials that assess whether the treatment works and remains reasonably safe in patients. Investors pay attention because that dose determines how convincing the upcoming trial results are likely to be, influences the size, cost and duration of further studies, and affects the chance of regulatory approval and commercial success—much like picking the right test speed to judge a new car's performance without risking damage.

dose escalation medical

"The dose escalation Phase 1 study is designed to determine the Maximum"

Dose escalation is the process of gradually increasing the amount of a treatment or substance over time. In finance, it can refer to slowly raising investments or commitments to manage risk and assess performance. For investors, understanding dose escalation helps gauge how companies or strategies adjust their approaches, which can impact future growth or stability.

hepatic clearance medical

"minimal bone/marrow uptake and expected hepatic clearance"

Hepatic clearance is the rate at which the liver removes a drug or chemical from the bloodstream by breaking it down or sending it into the bile for excretion. Like a water filter that determines how quickly impurities are flushed out, it controls how long a compound stays active, how often doses are needed, and the risk of side effects or interactions—factors that directly affect a drug’s safety, labeling, and commercial value to investors.

AI-generated analysis. How Rhea-AI works. Not financial advice.

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

On track to share data from first two dose levels in 2H 2026

Targeting KLK3 and leveraging the dual emission of Tb161 represents an innovative approach for radiotherapies in Prostate Cancer

Preclinical proof-of-concept mouse xenografts demonstrated RAD 402’s strong tumor targeting with minimal bone/marrow uptake and expected hepatic clearance

SYDNEY, March 27, 2026 (GLOBE NEWSWIRE) -- Radiopharm Theranostics (ASX:RAD, “Radiopharm” or the “Company”), a clinical-stage biopharmaceutical company focused on developing innovative oncology radiopharmaceuticals for areas of high unmet medical need, today announced that the first patient has been dosed in its first-in-human Phase 1 clinical trial of RAD 402, a monoclonal antibody targeting KLK3 radiolabelled with Terbium 161 being evaluated in advanced prostate cancer.

The Phase 1 clinical trial (NCT07259213) is designed to study the safety, tolerability, whole-body distribution, and preliminary clinical activity of RAD 402 in patients with advanced prostate cancer. The dose escalation Phase 1 study is designed to determine the Maximum Tolerated Dose (MTD) and/or recommended phase 2 dose (RP2D) for expansion.

“Dosing the first patient in our Phase 1 study of RAD 402 marks an important step forward for Radiopharm and for patients with advanced prostate cancer,” said Riccardo Canevari, CEO and Managing Director of Radiopharm Theranostics. “RAD 402 is a differentiated, first-in-class, next-generation radiotherapeutic designed to selectively target KLK3-expressing tumors while minimizing off-target exposure. With preclinical data demonstrating strong tumor uptake and minimal bone or marrow involvement, we are optimistic about its potential clinical profile. Advancing this program into the clinic reflects our continued commitment to delivering meaningful data across our portfolio this year. I like to take the opportunity to thank our partners, TerThera and Cyclotek, for the great support in supplying Tb161, radiolabelling, and distributing RAD 402.”

About RAD 402
RAD 402 (NCT07259213) is an anti-KLK3 monoclonal antibody radiolabelled with the radionuclide 161Tb that is being evaluated in a Phase 1/2a clinical trial for the treatment of prostate cancer. Prostate Specific Antigen (PSA) is a widely used biomarker to detect prostate cancer and is encoded by the KLK3 gene. KLK3 is highly expressed in prostate cancer cells along with most adenocarcinomas of the prostate including their metastases and has limited expression in sites outside of the prostrate. Preclinical proof-of-concept biodistribution studies of RAD 402 in mouse xenografts showed strong tumor targeting, limited bone and marrow uptake, and a hepatic excretion profile consistent with expectations for a monoclonal antibody.

About Radiopharm Theranostics
Radiopharm Theranostics is a clinical-stage radiotherapeutics company developing a world-class platform of innovative radiopharmaceutical products for diagnostic and therapeutic applications in areas of high unmet medical need. Radiopharm is listed on ASX (RAD) and on NASDAQ (RADX). The company has a pipeline of distinct and highly differentiated platform technologies spanning peptides, small molecules and monoclonal antibodies for use in cancer. The clinical program includes one Phase 2 and four Phase 1 trials in a variety of solid tumor cancers including lung, breast, prostate and brain metastases. Learn more at radiopharmtheranostics.com.

Authorised on behalf of the Radiopharm Theranostics board of directors by Chairman Paul Hopper.

For more information:
Riccardo Canevari
CEO & Managing Director
P: +1 862 309 0293
E: rc@radiopharmtheranostics.com

Anne Marie Fields
Precision AQ (Formerly Stern IR)
E: annemarie.fields@precisionaq.com

Paul Hopper
Executive Chairman
P: +61 406 671 515
E: paulhopper@lifescienceportfolio.com

Media
Matt Wright
NWR Communications
P: +61 451 896 420
E: matt@nwrcommunications.com.au

FAQ

What is RAD 402 and what target does RADX (ASX:RADX) aim with it?

RAD 402 is a KLK3-targeting monoclonal antibody radiolabelled with Terbium-161. According to the company, it is designed to selectively target KLK3-expressing tumors while limiting off-target exposure.

When will Radiopharm (ASX:RADX) report initial clinical data from the RAD 402 trial?

The company expects to share data from the first two dose levels in 2H 2026. According to the company, those initial readouts will cover safety, distribution, and preliminary clinical activity.

What did preclinical studies show about RAD 402’s biodistribution and clearance?

Preclinical mouse xenografts showed strong tumor uptake with minimal bone or marrow involvement. According to the company, RAD 402 demonstrated expected hepatic clearance in those studies.

What are the primary objectives of the Phase 1 study for RAD 402 (ASX:RADX)?

The Phase 1 trial will assess safety, tolerability, whole-body distribution and preliminary activity. According to the company, the dose-escalation will determine the MTD and/or recommended phase 2 dose.

Who is supplying Tb161 and supporting radiolabelling for RAD 402 in the RADX trial?

Radiopharm acknowledged partners TerThera and Cyclotek for supplying Tb161 and supporting radiolabelling and distribution. According to the company, those partners provided material and logistical support for the trial start.